Hey man! if you click on this link and scroll down to video number 5 and scroll to 2.50 you will see what he done. thats what im trying to achieve but isn't working for me the way it did for him...
AT the moment you pointed out in the video notice the bounding box of their image fills the entire window. Your bounding box is cropped to the edges of your art work. That's why it doesn;t work the same as in the video.
You need to pre-comp your atwork in a comp the size of your main comp, enable collapse transforms and then apply the repetile effect.